It has been known heretofore that building blocks or structural components may be prepared by exposing them to aqueous steam to enhance bonding or hardening of the materials used to prepare the blocks or structural components. This process is known as the "hydrothermal process" and is especially useful in manufacturing steam-hardened, low-weight gas concrete having hydrophobic properties. Also, German patent application No. 3,004,346 to Internationella Siporex AB, published Aug. 28, 1980, discloses that silicone oil can be added to a slurry consisting of a hydraulic binding agent, water and additives before it is molded and then exposed to aqueous steam.
It has been found that with the same amount of organopolysiloxane, building blocks or structural components prepared in accordance with the present invention and bonded or hardened with the aid of aqueous steam, exhibit much improved hydrophobicity in which the hydrophobicity is more evenly distributed on the surface or within the structure of the building blocks or structural components. Moreover, the pores are better distributed throughout the structural components and subsequent to bonding or hardening they can be more easily coated, for example with bitumen, than building blocks or structural components prepared in accordance with German patent application No. 3,004,346 containing silicone oil and then bonded or hardened with the aid of aqueous steam.
Therefore, it is an object of the present invention to provide a process for preparing structural components having improved hydrophobic properties. Another object of this invention is to provide structural components having improved hydrophobicity which is more evenly distributed throughout the structure as well as on the surface. Still another object of this invention is to provide a better distribution of pores throughout the structural components. A further object of this invention is to provide a process for preparing components which are easily coated.